1. Field of the Invention
The present invention relates to a wiring substrate, and more specifically, to a wiring substrate including a number of electrodes formed to protrude on a base and a method of manufacturing the same, and a semiconductor device using the wiring substrate and a method of manufacturing the same.
Priority is claimed on Japanese Patent Application No. 2012-082931, filed Mar. 30, 2012, the content of which is incorporated herein by reference.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
A smaller high-performance semiconductor device has been required for a small highly-functional system, and a “silicon wafer direct bonding” scheme of bonding wafers having a number of minute bumps functioning as electrodes formed therein has been examined.
In silicon wafer direct bonding, sealing through injection of, for example, a resin around bumps between wafers for the purpose of protecting the bumps after the bumps are electrically connected has been performed. However, when bonding between the wafers having minute bumps formed at high density is performed, such resin sealing is difficult. That is, if a bump diameter becomes small, a height of the bump correspondingly decreases. As a result, the gap between the wafers is narrowed and resin flow becomes difficult. If resin injection is forcedly performed in such a state, there is a possibility of voids being locally generated as a result of the resin not partially flowing.
In Japanese Unexamined Patent Application, First Publication No. 2009-94545, a method of performing bonding, with a resin used at the time of formation of bumps left, has been proposed. That is, a photosensitive resin is prepared on a wafer, electrode formation portions are opened, and then bumps are formed. Then, surfaces of the bumps and a surface of the photosensitive resin are polished at one time to be the same smooth surface, and then bonding is performed.
In this method, it is unnecessary to inject the resin after the bonding, making it unnecessary to consider injection failure of the resin.